A soot-producing engine is typically provided with electrostatic and cyclone-type separators that divide the soot-carrying exhaust gas of the engine into a particle-free stream and a particle-laden stream. The latter stream is fed to an afterburner that thermally and catalytically converts the soot mainly to harmless gas.
A typical such system as described in European patent document 0,152,623 has a housing forming a combustion chamber provided at one end with a feed tube coming from the exhaust-gas separators and feeding this combustion chamber with a particle-laden gas stream. The opposite end of the combustion chamber has an electrical heating element of large surface area. A filter is provided on the other side of this heating element and a vent tube opens into the top of the compartment on the other side of this filter. Combustion gas, normally air, is mixed with the incoming particle-laden gas stream in an annular area around the mouth of the feed pipe.
Such an arrangement is fairly bulky and, therefore, requires a large electrical heating element that consumes considerable electricity. In general operational efficiency is therefore relatively low.